text: Carbohydrates are an essential energy source for most life forms. In addition, polysaccharides formed from simpler carbohydrates are important structural components of many organisms such the cell walls of bacteria and plants.
  Carbohydrate are the products of plant photosynthesis and animal gluconeogenesis. Photosynthesis produces initially , a three-carbon atom containing sugar (a triose). This triose in turn may be converted into glucose (a six carbon atom containing sugar) or a variety of pentoses (five carbon atom containing sugars) through the Calvin cycle. In animals, the three carbon precursors lactate or glycerol can be converted into pyruvate which in turn can be converted into carbohydrates in the liver.